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Converting FFF feldspar


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#1 Jan jones

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Posted 13 October 2012 - 12:43 AM

Does anyone know what proportions of potash feldspar and nephelline syenite can be used to replace FFF feldspar in a glaze recipe. FFF feldspar does not seem to be available in Australia?

#2 JBaymore

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Posted 13 October 2012 - 09:29 AM

Can you post the typical analysis of the FFF feldspar you mention? If you do, I can recalculate it using other materials.

But to really be accurate I would also need the typical analysis of your OTHER raw materials that might be used to substitute..... the Neph. SY. and so on.

best,

.......................john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#3 Jan jones

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Posted 13 October 2012 - 10:27 PM

Can you post the typical analysis of the FFF feldspar you mention? If you do, I can recalculate it using other materials.

But to really be accurate I would also need the typical analysis of your OTHER raw materials that might be used to substitute..... the Neph. SY. and so on.

best,

.......................john

Thanks so much for the offer of help, I am a new hobby potter and using the lovely new book from Linda Bloomfield called : Colour in glazes, I do not have the precise composition of my materials from my supplier but, Am happy to test, test test.


The FFF FELDSPAR IS: SiO2 67.7, Al2O3 18.9, , Fe2O3 0.16, CaO 0.72, K2O 7.62, Na2o 4.84 LOI 0.05.

The Potash Feldspar is: SiO2 65.8, Al2O3 18.5, Fe2O3 0.1, CaO 0.38, K2O 12, Na2o 2.89, LOI 0.33

The Nephaline Syenite is: SiO2 60.5, Al2O3 23 , Fe2O3 0.1, CaO 1, K2O 1, Na2o 10.2 , LOI 0.2

I also have a problem with the rutile pink glaze from the book, , come , 8 oxidised, but is firing clear. the recipe is:

Any hints gratefully received.

Nephelline Syenite. 26
Whiting. 12
Lithium carb. 10
Barium carb. 3
Calcium borate fruit. 5
Quartz. , 44

+

Rutile. 1.5
Tin oxide. 4

Kind regards

Jan

#4 ayjay

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Posted 14 October 2012 - 10:45 AM

Calcium borate fruit. 5


Jan


That'll be the 5 portions for the day then. :D ;)

#5 Jan jones

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Posted 14 October 2012 - 07:28 PM


Calcium borate fruit. 5


Jan


That'll be the 5 portions for the day then. :D ;)



Tee hee, well spotted.




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